On Sat, Feb 25, 2017 at 04:10:37PM +0800, Tan Xiaojun wrote: > Recently I was using perf_fuzzer for testing in Hisilicon > D03/D05(arm64, linux-4.10-rc1). > > As we know perf_fuzzer will write a random value to procfs interface > of perf event(like sysctl_perf_cpu_time_max_percent). The value may be > 0 or 100, and I get logs like below: > > ---------------------------------- > [ 4046.358811] perf: Dynamic interrupt throttling disabled, can hang your system! > ---------------------------------- > > Most of the time, there is no problem, and the perf_fuzzer test can > end without any warings or errors. But there is a small probability > that triggers the RCU and watchdog (The log is attached at the end). > It hungs after local_irq_enable() in __do_softirq. > > I think this is due to the dynamic interrupt throttling disabled and > too many hardware interruptions come. So I limit the > sysctl_perf_cpu_time_max_percent can only be set 1 to 99 in the kernel > codes. I test more than 20 times in D03, and there are no errors or > warnings in the test. > > So I want to ask: > > 1)Is it a problem or not? (It has already given you a warning.) > > 2)If it is, where we will fix it more appropriate, perf_fuzzer(not set > 0 or 100) or kernel(limit 1 to 99), or maybe it is the bug of > hardware(too many hardware interruptions)? I think the best would be if the fuzzer would not set 0,100, those are clearly 'unsafe' settings and you pretty much get to keep the pieces. I would like to preserve these settings for people that 'know' what they're doing and are willing to take the risk, but clearly, when you take the guard-rails off, things can come apart. -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|